A. Field of Invention
This invention pertains to the art of methods and apparatuses for variable speed drive assemblies, and more specifically to a variable speed drive assembly using a pair of pulley belt systems for use in a lawn tractor.
B. Description of the Related Art
It is known in the art to provide vehicles with drive assemblies that can vary the speed of the vehicle. For some vehicles, such as lawn tractors, it is known to use drive assemblies that include a pair of pulley belt systems. Such pulley belt systems generally work well for the intended purpose. However, these pulley belt systems require the use of one or more idler pulleys to create tension on the belts in the system. The use of these idler pulleys increases the amount of parts necessary and also increases the cost of pulley belt systems.
An attempt to reduce this problem can be found in U.S. Pat. No. 6,364,794 which describes a vehicle drive assembly having a variable speed drive assembly and a directional control transmission assembly operable between a forward and a reverse drive condition. The drive assembly includes a linkage assembly that operates to move a variable speed drive assembly toward a directional control transmission assembly to increase the speed of the vehicle. The prior art employs the use of springs rather than idler pulleys. One difficulty with this drive assembly is that the double pulley cannot be efficiently adjusted. Another difficulty is that a total of four springs are required to operate the drive assembly and to provide the proper tension on the belts and the proper movement of the variable speed drive assembly. Still another difficulty is that, once the ignition key is switched to the “off” position, the drive system belts cannot be easily disengaged to place the vehicle in a neutral drive condition. The prior art also requires a brake to disengage the belt.
The present invention provides methods and apparatuses for eliminating an idler pulley and using a minimum of springs to tension the system belts. The present invention eliminates two unnecessary springs used in the prior art and also provides methods of disengaging the system belts when there is no applied power to the drive assembly. The difficulties inherit in the art are therefore overcome in a way that is simple and efficient, while providing better and more advantageous results.